(a) Field
The present invention relates to a thin film transistor (“TFT”) panel and a liquid crystal display (“LCD”) apparatus. More particularly, the present invention relates to a TFT panel and an LCD apparatus capable of improving side visibility without a decrease in transmittance.
(b) Description of the Related Art
An LCD apparatus, which is one of the most widely used flat panel display apparatuses, includes two panels having electric field generating electrodes, such as pixel electrodes and a common electrode, and a liquid crystal layer interposed therebetween. The LCD apparatus displays an image by applying a voltage to the electric field generating electrodes to generate an electric field in the liquid crystal layer and determining alignment of liquid crystal molecules in the liquid crystal layer to control polarization of incident light. In the LCD apparatus, by applying the voltage to the two electrodes to generate the electric field in the liquid crystal layer, a desired image is obtained by adjusting an intensity of the electric field to adjust transmittance of light passing through the liquid crystal layer. At this time, in order to prevent a deterioration phenomena caused by applying the electric field to the liquid crystal layer in one direction for an extended time, the polarities of the data voltages with respect to the common voltage are inverted in units of a frame, a row, or a pixel.
Among such LCD apparatuses, an LCD apparatus with a vertical alignment mode, in which liquid crystal molecules are arranged such that major axes of the liquid crystal molecules are perpendicular to the upper and lower panels in a state when no electric field is generated, is of interest, since it has a high contrast ratio and can easily provide a wide reference viewing angle. Here, the reference viewing angle means a viewing angle having a contrast ratio of 1:10 or an effective angle in inversion of brightness between gray scales.
Methods of embodying a wide viewing angle in an LCD apparatus with a vertical alignment mode include a method of forming apertures in the electric field generating electrodes and a method of forming protrusions on the electric field generating electrodes. Since the direction in which the liquid crystal molecules are tilted can be determined by the use of the apertures and the protrusions, the reference viewing angle can be widened by variously arranging the apertures and the protrusions to distribute the tilt direction of the liquid crystal molecules in various directions.
However, the LCD apparatus with a vertical alignment mode has side visibility lower than front visibility. For example, in the case of an LCD apparatus with a patterned vertical alignment (“PVA”) mode having apertures, an image becomes brighter toward the side, and in some cases, the difference in brightness between high gray scales may disappear rendering the profile of the image vague.
In order to solve such problems, there has been proposed a technique for providing different transmittances by dividing one pixel into two subpixels, coupling the two subpixels in a capacitive manner, and providing different voltages to the two subpixels by directly applying a voltage to the one subpixel and dropping a voltage in the other subpixel due to the capacitive coupling.
However, in the above technique, the transmittances of the two subpixels cannot be accurately adjusted.
In particular, the transmittances of different colors of light are different from each other. However, it is difficult to obtain different voltage combinations for different colors. In addition, since conductive members for the capacitive coupling must be added, an aperture ratio deteriorates and, due to a voltage drop caused by the capacitive coupling, the transmittance decreases.